Total attendance for the month = (Number of Sundays × Average attendance on Sundays) + (Number of other days × Average attendance on other days) Average attendance per day = Total attendance for the month ∕ Total number of days in the month Calculation: We have, ⇒ Number of Sundays in 30 days =5 ⇒ Number of other days in 30 days =30−5=25 Using the formula, ⇒ Total attendance for the month =(5×410)+(25×230) ⇒ Total attendance for the month =2050+5750 ⇒ Total attendance for the month =7800 Now, ⇒ Average attendance per day =7800∕30 ⇒ Average attendance per day =260 ∴ The average attendance per day of a month of 30 days beginning with Sunday is 260 .